Field of the Invention
The present invention relates to an optical system and an image pickup apparatus including the same, which are suitable for, for example, an image pickup optical system for a digital still camera, a digital video camera, a television (TV) camera, a monitoring camera, a silver-halide camera, or the like.
Description of the Related Art
As an image pickup optical system to be used in an image pickup apparatus such as a digital camera or a video camera, there has been known an image pickup optical system having a long focal length and a large aperture. There is a strong demand for the image pickup optical system to have high optical characteristics, even though a total lens length thereof is short and an entire system thereof is compact. Also demanded to the image pickup optical system is being capable of achieving high-speed focusing operation.
Hitherto, as a focusing type, there has been known an inner focus type in which a light-weight lens unit positioned inside an image pickup optical system is configured to move for focusing. Further, there is a need for image pickup optical systems having a long focal length to have an image stabilization function for correcting a blur of a taken image because such image pickup optical systems are easily affected by camera shake.
Hitherto, as a method of correcting a blur of a taken image, there has been known a configuration in which a part of lens units of an image pickup optical system is configured to move in a direction having a vertical direction component with respect to an optical axis such that an imaging position is moved to the vertical direction with respect to the optical axis.
In each of Japanese Patent Application Laid-Open No. 2012-242504 and Japanese Patent Application Laid-Open No. 2014-74783, there is disclosed an image pickup optical system that includes an inner focus type focusing mechanism, and further has an image stabilization function.
In an image pickup optical system including an inner focus type focusing mechanism, aberration deviation tends to increase during focusing. Further, in an image pickup optical system employing an image blur correction method in which a part of lens units is used as an image stabilization lens unit, decentering aberrations tend to be generated by a large amount during image stabilization.
Thus, it is important to arrange a focusing lens unit and an image stabilization lens unit at appropriate positions.